wrote some ffi functions and interfaces

tested the fact that the rust library could be used in a embedded application

libautobar/src/lib.rs

@@ -1,3 +1,26 @@
+#![no_std]
+
+use core::panic::PanicInfo;
+
+#[panic_handler]
+fn panik(_panic_state: &PanicInfo) -> ! {
+    loop {}
+}
+
+extern {
+    fn gpio_put_explict(pin: i32, status: bool) -> i32;
+    fn sleep_ms(time: i32) -> i32;
+}
+
+#[no_mangle]
+pub extern "C" fn set_and_sleep(pin: i32, status: bool, time: i32) -> () {
+    unsafe {
+        gpio_put_explict(pin, status);
+        sleep_ms(time);
+    }
+}
+
+// this is just a mock test, supposed to pass
 #[cfg(test)]
 mod tests {
     #[test]